Cardinal Health Inc. has added another three years to its recently renewed contract with its largest customer, CVS Caremark Corp., as the pharmaceutical players create a joint venture to lower their supply costs from generic drug manufacturers.

Dublin-based Cardinal (NYSE:CAH) and CVS (NYSE: CVS) announced Tuesday that the joint venture for generics would launch by July. They say the 10-year agreement creates the nation’s largest entity to source generics – which despite their lower prices bring better margins to distributors and retailers.